This invention relates to lubrication by atomization of lubricant carried by a gas, typically compressed air.
The bearings of machine-tool shafts and spindles and rolling-contact bearings used in rolling mills and levelers for steelworks are generally lubricated by a centralized supply of lubricant delivering a flow of lubricant carried by a gas, typically compressed air. The mixture of air and lubricant is carried by pipes to the lubrication points where the lubricant must be delivered in the form of a mist of fine droplets of lubricant carried by the gas stream. The lubricant is carried along the pipes to the lubrication points in the form usually of a film of lubricant propelled by the air current. This mixture must therefore be modified to turn it into a mist consisting of a multitude of minute droplets of lubricant for each lubrication point.
The various lubrication points are therefore provided with divider devices designed to atomize the lubricant into minute droplets in the gas stream. German Utility Model Application 297 24492, which corresponds to U.S. Pat. No. 6,257,370 (REBS), describes the use of a connection piece which has an angular region in a supply bore followed by a tapering funnel-shaped region defining a dispensing chamber. Inside this chamber, lubricant droplets accumulate in dead regions from where they are picked up by the gas stream. A distribution barrel is coupled to the connection piece and comprises longitudinal channels which distribute the lubricant/air mixture.
A similar arrangement is found in German Utility Model Application 20 2007 005930 (REBS), which teaches the formation of turbulence in the supply stream by a funnel-shaped part located in a connection piece coupled to a distribution body.
In these devices, however, it is observed that the lubricating mixture is not correctly distributed when the backpressure downstream of the divider device is not the same in all the distribution channels.
The same fault is found in a divider device described in German Utility Model Application 20 2007 009472 (Lincoln), where the distribution between the different channels is effected by a conical piece which divides up the flow. International Patent Application WO 2005/113 157 (REBS) attempts to improve the distribution of lubricant/air mixtures by creating a swirling flow by having outlet orifices arranged radially. The aim is to create a helical swirl in a dispensing chamber located between a connection piece and a distribution barrel. The same type of construction is also found in German Utility Model Application DE 203 11631 (Delimon), which uses a swirl chamber and an expansion chamber between the supply and distribution of the lubricant/air mixture.
These devices do not perform satisfactorily in practice.
Additionally, all known devices are found to work defectively because of lubricant not being completely modified in the distribution channels following the divider devices. This lubricant builds up inside the device and interferes with the operation of the divider.